First, I don't know if the NES has the memory necesary to remember which puzzle was solved, if Zak has talked to this character... Etc. Then, the world in Zak McKracken it's too big for a NES, for a NES the mazes and at least all the part of the game that happens in Mars should be removed. Then, programming a Cashcard system would be hard because of the NES memory problem that I mentioned above.

That's why just Maniac Mansion (The less complex of LucasArts games) was the adapted one, what I think LucasArts should have done is porting the game on the Super Nintendo, or on the Megadrive (As Monkey Island 1), the graphics could be like the FM-Towns version, and I would like to see Zak like one of the Super Nintendo classics, along with Zelda 3 and Chrono Trigger.